public override void WindowControllerDidLoadNib (NSWindowController windowController)
{
base.WindowControllerDidLoadNib (windowController);
LoadImages ();
history = new History (navigationCells);
outlineView.DataSource = new DocTreeDataSource (this);
outlineView.Delegate = new OutlineDelegate (this);
webView.DecidePolicyForNavigation += HandleWebViewDecidePolicyForNavigation;
}